Hi, On 2020-01-16 17:25:00 +0100, Tomas Vondra wrote: > On Thu, Jan 16, 2020 at 10:27:01AM -0500, Tom Lane wrote: > > Andres Freund <and...@anarazel.de> writes: > > > ... I thought you were asking whether > > > any additional memory could just be avoided... > > > > Well, I was kind of wondering that, but if it's not practical then > > preallocating the space instead will do. > > > > I don't think it's practical to rework the checks in a way that would > not require allocations. Maybe it's possible, but I think it's not worth > the extra complexity. > > The attached fix should do the trick - it pre-allocates the space when > creating the context. There is a bit of complexity because we want to > allocate the space as part of the context header, but nothin too bad. We > might optimize it a bit by using a regular bitmap (instead of just an > array of bools), but I haven't done that.
I don't get why it's advantageous to allocate this once for each slab, rather than having it as a global once for all slabs. But anyway, still clearly better than the current situation. - Andres
